New research challenges long-held beliefs about teh Earth’s core, suggesting it may not be a solid sphere of iron as previously thought. A study published this week details evidence supporting a “superionic phase” within the inner core-a state where iron remains solid but lighter elements flow freely-possibly explaining anomalies detected in seismic wave activity. scientists recreated core conditions in a laboratory using high-powered “light gas guns” to validate the model and gain insights into the planet’s magnetic field and geological processes.
HABER MERKEZİ
Oluşturulma Tarihi: Aralık 27, 2025 11:54
Earth’s inner core may not be as solid as previously thought, according to new research suggesting a bizarre state of matter known as a “superionic phase.”
For decades, the Earth’s inner core has been understood as a solid sphere of iron, held rigid by immense pressure despite scorching temperatures. While the outer core is molten, scientists believed the inner core remained solid due to the crushing weight above. However, recent analysis of seismic data – specifically, the speed of shear waves traveling through the core – revealed these waves move slower than expected, hinting at a more complex internal structure. This led researchers to question whether the inner core was “solid, but not as hard as we thought.”
Now, a new experimental study points to a peculiar physical state: the superionic phase. In this phase, the iron component of the alloy remains solid, maintaining its crystalline structure, while lighter atoms, like carbon, move fluidly within that solid lattice. Essentially, the material exists as both “orderly and solid” and “carrying a mobile component” simultaneously. This behavior could explain the inner core’s unexpectedly elastic response, often described as feeling “soft like butter.”
WHY IS THE CORE SO SOFT?
A material’s “hardness” is largely determined by its resistance to deformation. Shear waves test this resistance by propagating through a material with a sideways “bending” motion. Slower shear wave speeds suggest the internal structure offers less resistance to this bending. In the superionic scenario, while the iron lattice remains intact, the mobility of carbon atoms reduces the overall rigidity, meaning the inner core doesn’t behave like a completely solid metal sphere. Understanding the inner core’s composition is crucial to understanding the planet’s magnetic field and overall geological activity.
Researchers also note that measurements like the Poisson ratio – frequently used in seismology – align with this model. The Poisson ratio describes how much a material “swells” sideways when compressed. Higher values measured for the inner core indicate it possesses a more “flexible and compressible” character than previously assumed.
A ‘GUN’ TEST OF THE CORE
Directly observing the conditions within the Earth’s core is impossible, so the research team attempted to recreate “instant core conditions” in a laboratory setting. They used two-stage light gas guns to fire tiny particles of iron-carbon alloy at a target at speeds exceeding 7 kilometers per second. The resulting shockwave briefly subjected the sample to pressures around 140 gigapascals and temperatures around 2,600 Kelvin.
While these values aren’t as extreme as the estimated 330-360 gigapascals of pressure and 5,000-6,000 Kelvin of temperature within the Earth’s core, researchers say the critical goal was to test whether the material would transition to “superionic behavior.” Even though these conditions lasted only between nanoseconds and microseconds, lasers and fast sensors were able to record parameters like density, temperature, and wave propagation.
The results showed a distinct drop in the shear wave speed of the iron-carbon alloy. This means the physical model explaining the “slow shear waves” observed in the inner core has now been experimentally supported for the first time. Scientists believe this approach could open new avenues for understanding the internal structure of “Earth-like” planets with similar cores.
Another important aspect of this research relates to the Earth’s magnetic field: Earth’s magnetic shield is linked to the heat and motion dynamics of conductive materials deep within the planet. A more “dynamic” internal structure of the inner core could provide new clues for unraveling the intricacies of this powerful engine.
